306 STUDIES IN FOSSIL BOTANY 



The group, as we shall see presently, was in all 

 probability an extensive one in Palaeozoic times, but 

 we will give our chief attention to those genera in 

 which there is evidence as to the reproductive as well 

 as the vegetative organs. 



A. Zygopteris Group 



i . Zygopteris. — We will first take the genus 

 Zygopteris, founded by Corda in 1845, on a species 

 described by Sprengel and Cotta a good many years 

 earlier. A number of species have now been recorded, 

 but in many of them the structure of the petiole only 

 is known ; our knowledge of the stem extends to four 

 species : Z. Brongniarti , Ren., 1 from the Permian of 

 Autun, in France ; Z. scandens, Stenz., 2 from a similar 

 horizon in Bohemia and Saxony ; Z. Grayi (Will.), 3 

 and Z. corrugata (Will.), 4 from the Lower Coal-measures 

 of England. Z. scandens and Z. Grayi were regarded 

 by Williamson, in spite of the difference in geological 

 age, as identical. The anatomical description will be 

 based chiefly on Z. Grayi, which may best serve 

 as the type of the genus. We shall find that, 

 throughout this family, our knowledge is for the 

 most part based on petrified specimens, so that while 

 the anatomical data are full and fairly satisfactory, 



1 Renault, Cours de botanique fossile, vol. iii. chap. viii. 1883 ; for his 

 original memoirs see Ann. des sci. nat. (Bot.), ser. vi. vols. i. and iii. 

 1875-76. 



2 Stenzel, "Die Gattung Tubicaulis," Cotta; Bibliotheca Botanica, 

 tassel, 1889. 



3 Williamson, " Organisation of Fossil Plants of Coal-measures," Part 

 xv. Phil. Trans. 1889, B. 



4 Williamson, op. cit. Part viii. Phil. Trans, vol. 167, 1877. 



